24 results on '"Chunsen Li"'
Search Results
2. Mechanistic insights into the crucial roles of Glu76 residue in nickel-dependent quercetin 2,4-dioxygenase for quercetin oxidative degradation
- Author
-
Jinshuai Song, Qianqian Lu, Chunsen Li, and Xueyuan Yan
- Subjects
010405 organic chemistry ,Chemistry ,Stereochemistry ,Mutant ,Protonation ,010402 general chemistry ,01 natural sciences ,Catalysis ,0104 chemical sciences ,Residue (chemistry) ,chemistry.chemical_compound ,Dioxygenase ,Reactivity (chemistry) ,Physical and Theoretical Chemistry ,Proton-coupled electron transfer ,Quercetin - Abstract
Combined QM/MM calculations and MD simulations are utilized to investigate the detailed mechanisms of reactions catalyzed by wild-type nickel-dependent quercetin 2,4-dioxygenase (Ni-QueD) and its Glu76Asp and Glu76Gln mutants. The conserved nickel-ligating Glu76 residue in the deprotonated form is found to be essential for initiating the catalytic reaction by proton coupled electron transfer process. The generated protonated Glu76 promotes the subsequent reaction by regulating hydrogen-bonding (H-bonding) interaction with the carbonyl groups of quercetin. Investigations of Glu76Gln and Glu76Asp mutants show that mutation of Glu76 suppresses such H-bonding interaction and results in the lower catalytic activity observed experimentally. Thus, our results reveal the critical role of Glu76 residue in steering the reactivity of Ni-QueD. This work is not only useful for better understanding the mechanisms of reactions catalyzed by other metal ion-dependent QueDs, but also provides insights into how enzymes achieve specific reactions by utilizing H-bonding interaction from the metal center-ligating residues.
- Published
- 2020
3. An Uncommon Hypervalent Fluorooxosilicophosphate
- Author
-
Chunsen Li, Qingran Ding, Maochun Hong, Lina Li, Junhua Luo, Yusong Wang, Shuai Liu, Han Xiao, Sangen Zhao, and Yanqiang Li
- Subjects
Silicon ,010405 organic chemistry ,Phonon ,Organic Chemistry ,Hypervalent molecule ,Species diversity ,chemistry.chemical_element ,Ionic bonding ,General Chemistry ,Conductivity ,010402 general chemistry ,01 natural sciences ,Biochemistry ,0104 chemical sciences ,chemistry ,Chemical physics ,Ionic conductivity ,Species richness - Abstract
The species diversity of silicon (including traditional tetrahedral coordinated silicon and hypervalent penta- and hexa-coordinate silicon) gives rise to the structural richness and diverse properties of silicates. Among these silicon species, hypervalent silicon is very rare, not to mention almost unexplored mixed-anion hypervalent fluoroxosilicate species. In this work, we successfully obtained a mixed-anion fluorooxosilicophosphate Na4Si2PO4F9 consisting of two uncommon hypervalent fluoroxosilicate species, namely, trans-SiO2F4 species and SiOF5 species. To the best of our knowledge, such hypervalent silicon species are reported for the first time in inorganic compounds. Remarkably, the coexistence of two distinct hypervalent fluoroxosilicate species in one compound is somewhat conflicted with Pauling's parsimony rule, but it indeed achieves an unlikely connection by PO4 and our phonon dispersion calculation confirms the structure stability of Na4 Si2 PO4 F9 . Temperature-dependent conductivity measurements show that Na4 Si2 PO4 F9 is a promising solid ionic conductor with a high conductivity of 4.0×10-5 S⋅cm-1 at 700 K and a low active energy of about 53.1 KJ⋅mol-1 . This work will enrich the structure chemistry of silicates and may provide a new platform for solid ionic batteries.
- Published
- 2019
4. Mechanistic Insights into the Directing Effect of Thr303 in Ethanol Oxidation by Cytochrome P450 2E1
- Author
-
Peng Wu, Chunsen Li, Walter Thiel, Jinshuai Song, and Qianqian Lu
- Subjects
chemistry.chemical_classification ,Ethanol ,biology ,010405 organic chemistry ,Cytochrome P450 ,Alcohol ,General Chemistry ,CYP2E1 ,010402 general chemistry ,Hydrogen atom abstraction ,01 natural sciences ,Combinatorial chemistry ,Catalysis ,0104 chemical sciences ,chemistry.chemical_compound ,Enzyme ,chemistry ,Alcohol oxidation ,biology.protein - Abstract
There is a long-standing mechanistic consensus that alcohol oxidation by cytochrome P450 enzymes is triggered by hydrogen abstraction from the α-C–H bond of the alcohol. Through combined molecular ...
- Published
- 2019
5. Atomically thin heavy-metal-free ZnTe nanoplatelets formed from magic-size nanoclusters
- Author
-
Guohua Jia, Lai-Chang Zhang, Heng Yang, Mark A. Buntine, Sheng Wang, Minyi Zhang, Wei Chen, Shaghraf Javaid, Fei Wang, Chunsen Li, and Xuyong Yang
- Subjects
business.industry ,General Engineering ,chemistry.chemical_element ,Bioengineering ,Nanotechnology ,02 engineering and technology ,General Chemistry ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,Atomic and Molecular Physics, and Optics ,0104 chemical sciences ,Nanoclusters ,Semiconductor ,chemistry ,Metal free ,Cdse nanocrystals ,Metastability ,General Materials Science ,0210 nano-technology ,Tellurium ,business ,Wurtzite crystal structure - Abstract
Atomically thin colloidal quasi-two-dimensional (2D) semiconductor nanoplatelets (NPLs) have attracted tremendous attention due to their excellent properties and stimulating applications. Although some advances have been achieved in Cd- and Pb-based semiconductor NPLs, research into heavy-metal-free NPLs has been reported less due to the difficulties in the synthesis and the knowledge gap in the understanding of the growth mechanism. Herein wurtzite ZnTe NPLs with an atomic thickness of about 1.5 nm have been successfully synthesized by using Superhydride (LiEt3BH) reduced tributylphosphine–Te (TBP-Te) as the tellurium precursor. Mechanistic studies, both experimentally and theoretically, elucidate the transformation from metastable ZnTe MSC-323 magic-size nanoclusters (MSCs) to metastable ZnTe MSC-398, which then forms wurtzite ZnTe NPLs via an oriented attachment mechanism along the [100] and [002] directions of the wurtzite structure. This work not only provides insightful views into the growth mechanism of 2D NPLs but also opens an avenue for their applications in optoelectronics.
- Published
- 2020
6. Optical Resolution of the Water-Soluble Ti4(embonate)6 Cages for Enantioselective Recognition of Chiral Drugs
- Author
-
Lv-Bing Yuan, Chunsen Li, Guang-Hui Chen, Lei Zhang, Jian Zhang, Qipu Lin, Yan-Ping He, and Jinshuai Song
- Subjects
Materials science ,010405 organic chemistry ,General Chemical Engineering ,Resolution (electron density) ,Enantioselective synthesis ,General Chemistry ,010402 general chemistry ,Quantitative Biology::Other ,01 natural sciences ,0104 chemical sciences ,Condensed Matter::Soft Condensed Matter ,Condensed Matter::Materials Science ,Crystallography ,Water soluble ,Enantiopure drug ,Physics::Atomic and Molecular Clusters ,Materials Chemistry ,Physics::Chemical Physics - Abstract
Synergetic optical resolution and chiral amplification of tetrahedral Ti4L6 cages by enantiopure coordination cations have been realized in this work. Anionic ΔΔΔΔ-[Ti4L6] and ΛΛΛΛ-[Ti4L6] cages (L...
- Published
- 2018
7. B‐Heterocyclic Carbene Arising from Charge Shift: A Computational Verification
- Author
-
Zhimin Wang, Fan Fan, Yirong Mo, Jinshuai Song, Chunsen Li, and Congjie Zhang
- Subjects
Tetracoordinate ,010405 organic chemistry ,Chemistry ,Ligand ,Organic Chemistry ,Ionic bonding ,General Chemistry ,010402 general chemistry ,01 natural sciences ,Catalysis ,0104 chemical sciences ,Adduct ,Crystallography ,chemistry.chemical_compound ,Ab initio quantum chemistry methods ,Singlet state ,Lewis acids and bases ,Carbene - Abstract
1-Borabicyclo[1.1.0]but-2(3)-ene (1BB) is a singlet biradical with two single electrons that can form an ionic resonance structure through a charge shift. The ionic resonance structure is a B-heterocyclic carbene (BHC), which can act as a carbene, Lewis base, or L- and Z-type ligand, to give adducts and complexes. Through a range of quantum methods, four types of stable compounds (A-D) derived from 1BB have been designed. These compounds retain the unique features of 1BB. As a consequence, the structures, stability, and Wiberg bond indices of the Lewis adducts of A-D with Lewis acids (BePh2 , BH3 , AlH3 , AlCl3 , C5 BH5 , and C13 BH9 ) and CuI , AgI , and AuI complexes have been investigated. Results show that A-D can indeed react as carbenes. Interestingly, compounds A-D, as L-type ligands, can attach to BePh2 , BH3 , AlH3 , AlCl3 , C5 BH5 , C13 BH9 , and CuCl and form compounds with planar tetracoordinate carbon (ptC), whereas Z-type ligands A-D can bind to AgCl and AuCl to provide complexes with planar tetracoordinate boron (ptB). In addition, the binuclear complexes of ClX(1BB)CuCl (X=Ag, Au) have been studied and A-D behave as both L- and Z-type ligands, in which these complexes contain both ptC and ptB. Thus, a novel method for designing compounds with ptC and ptB is presented. These rationally designed compounds involve the elements of carbene, ptC, ptB, and L- and Z-type ligands, and are expected to be unique and useful in experimental chemistry once they are synthesized.
- Published
- 2018
8. Integrating the g-C3N4 Nanosheet with B–H Bonding Decorated Metal–Organic Framework for CO2 Activation and Photoreduction
- Author
-
Haixia Zhang, Yang Li, Jing Wei, Chunsen Li, Guilan Xu, Jinhua Ye, Xin Wu, Huabin Zhang, and Jian Zhang
- Subjects
Materials science ,Hydrogen bond ,Composite number ,General Engineering ,Graphitic carbon nitride ,General Physics and Astronomy ,02 engineering and technology ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,0104 chemical sciences ,chemistry.chemical_compound ,chemistry ,Chemical engineering ,Imidazolate ,Photocatalysis ,General Materials Science ,Metal-organic framework ,0210 nano-technology ,Carbon nitride ,Nanosheet - Abstract
BIF-20, a zeolite-like porous boron imidazolate framework with high density of exposed B–H bonding, is combined with graphitic carbon nitride (g-C3N4) nanosheets via a facile electrostatic self-assembly approach under room temperature, forming an elegant composite BIF-20@g-C3N4 nanosheet. The as-constructed composite preferably captures CO2 and further photoreduces CO2 in high efficiency. The photogenerated excitations from the carbon nitride nanosheet can directionally migrate to B–H bonding, which effectively suppresses electron–hole pair recombination and thus greatly improves the photocatalytic ability. Compared to the g-C3N4 nanosheet, the BIF-20@g-C3N4 nanosheet composite displayed a much-enhanced photocatalytic CO2 reduction activity, which is equal to 9.7-fold enhancements in the CH4 evolution rate (15.524 μmol g–1 h–1) and 9.85-fold improvements in CO generation rate (53.869 μmol g–1 h–1). Density functional theory simulations further prove that the presence of B–H bonding in the composite is fav...
- Published
- 2018
9. HOTf-Catalyzed Alkyl-Heck-type Reaction
- Author
-
Liang Ge, Yajun Li, Huan Zhou, Wujun Jian, Hongli Bao, Chunsen Li, and Jinshuai Song
- Subjects
chemistry.chemical_classification ,Multidisciplinary ,Primary (chemistry) ,010405 organic chemistry ,Alkylation ,010402 general chemistry ,01 natural sciences ,0104 chemical sciences ,Catalysis ,chemistry.chemical_compound ,chemistry ,Heck reaction ,Organic chemistry ,Organic synthesis ,lcsh:Q ,lcsh:Science ,Alkyl - Abstract
Summary: The Heck reaction, along with other cross-coupling reactions, led to a revolution in organic chemistry. In the last 50 years, metal-catalyzed, photo-induced, or base-mediated Heck and Heck-type reactions have been elegantly developed. Brønsted acid-catalyzed Heck (or Heck-type) reactions are still unknown, however. By introducing alkyl peroxides as the key intermediates, primary, secondary, and tertiary aliphatic carboxylic acids are therefore applied here in a one-pot Brønsted acid-catalyzed Heck-type reaction, to deliver E-alkenes exclusively in most cases. The use of HOTf is vital to the reaction, whose mechanism is supported by both experimental and computational results. This method can be expanded to the direct alkylation of complex natural products. : Organic Synthesis; Organic Chemistry Methods; Natural Product Synthesis Subject Areas: Organic Synthesis, Organic Chemistry Methods, Natural Product Synthesis
- Published
- 2018
10. A theoretical study on the mechanism of hydrogenation of carboxylic acids catalyzed by the Saito catalyst
- Author
-
Chunsen Li, Minyi Zhang, Jing Wei, Jinshuai Song, and Qianqian Lu
- Subjects
chemistry.chemical_classification ,010405 organic chemistry ,Hydride ,Carboxylic acid ,chemistry.chemical_element ,Alcohol ,010402 general chemistry ,01 natural sciences ,Aldehyde ,Combinatorial chemistry ,Heterolysis ,0104 chemical sciences ,Catalysis ,Ruthenium ,Inorganic Chemistry ,chemistry.chemical_compound ,chemistry ,Catalytic cycle - Abstract
The mechanism of the ruthenium carboxylate-catalyzed hydrogenation of carboxylic acids was investigated by using density functional theory (DFT) calculations. The novel mechanism including two hydrogenation cycles was proposed for this reaction. The first cycle is the hydrogenation of the carboxylic acid to an aldehyde, while the second cycle is the hydrogenation of the aldehyde to an alcohol. These two catalytic cycles share similar elementary steps, including H2 heterolysis, hydride migration of the carboxylic acid or aldehyde, and catalyst regeneration. In this hydrogenation mechanism, the carboxylic acid is not only a reactant, but also an important proton source. Furthermore, the noncovalent interaction (e.g. hydrogen bonding interaction) between the ligand and carboxylic acid substrate could promote the hydrogenation of the carboxylic acid through stabilizing the transition state of the most energy-demanding step (i.e., hydride migration in the first catalytic cycle). Besides, the strong electron-donating ability of the dppb ligand could also facilitate the hydride migration.
- Published
- 2018
11. Brønsted base-catalyzed annulation of allyl ketones and alkynyl 1,2-diketones
- Author
-
Xinyue Zhan, Jinshuai Song, Xinqiang Fang, Shuang Yang, Miao Meng, Jian Liu, Xiangwen Kong, Chunsen Li, and Min Zeng
- Subjects
Annulation ,010405 organic chemistry ,Chemistry ,organic chemicals ,Metals and Alloys ,food and beverages ,General Chemistry ,010402 general chemistry ,01 natural sciences ,Medicinal chemistry ,Catalysis ,0104 chemical sciences ,Surfaces, Coatings and Films ,Electronic, Optical and Magnetic Materials ,chemistry.chemical_compound ,Important research ,Intramolecular force ,Electrophile ,Materials Chemistry ,Ceramics and Composites ,Organic synthesis ,Brønsted–Lowry acid–base theory ,Bond cleavage - Abstract
The discovery of new reaction modes mediated by easily available substrates is an important research topic in organic synthesis. Allyl ketones and related compounds have been demonstrated to undergo γ- or α-selective additions to different electrophiles. We disclose here the Brønsted base-catalyzed reaction of allyl ketones and alkynyl 1,2-diketones, which undergo a unique α-selective addition/intramolecular aldol-type annulation/C-C bond cleavage process, and a series of 2-acyloxycyclopent-3-enones can be obtained under very mild conditions.
- Published
- 2018
12. Large Second-Harmonic Generation Responses Achieved by the Dimeric [Ge2Se4(μ-Se2)]4– Functional Motif in Polar Polyselenides A4Ge4Se12 (A = Rb, Cs)
- Author
-
Minyi Zhang, Chunsen Li, Wang Guoqiang, Hui-Yi Zeng, Shu-Fang Li, Guo-Cong Guo, Jin-Shun Huang, Yu-Hang Fan, Bin-Wen Liu, Xiao-Ming Jiang, and Yong-Fei Su
- Subjects
Chemistry ,General Chemical Engineering ,Second-harmonic generation ,Charge (physics) ,02 engineering and technology ,General Chemistry ,010402 general chemistry ,021001 nanoscience & nanotechnology ,Laser ,Ring (chemistry) ,01 natural sciences ,0104 chemical sciences ,law.invention ,Crystallography ,Atomic orbital ,law ,Materials Chemistry ,Polar ,Density functional theory ,0210 nano-technology ,Lone pair - Abstract
Two new polar polyselenides Rb4Ge4Se12 (1) and Cs4Ge4Se12 (2) with rarely reported dimeric [Ge2Se4(μ-Se2)]4− units were synthesized. They present large second-harmonic generation (SHG) intensities of 7.5 and 6.5 times that of the benchmark AgGaS2 with type I phase-matching behavior, high laser induced damaged thresholds, wide transmission region and congruently melting behavior, making them excellent candidates for IR nonlinear optical (NLO) applications. The SHG functional motifs of both compounds are determined to be [Ge2Se4(μ-Se2)]4− unit by time-dependent density functional theory calculation, which further reveals that charge transfers from the lone pairs of terminal Se atoms to the five σ* orbitals of five-membered ring Ge2Se3 have a predominant contribution to the total SHG effect.
- Published
- 2017
13. Rhodium-Catalyzed Azide–Alkyne Cycloaddition of Internal Ynamides: Regioselective Assembly of 5-Amino-Triazoles under Mild Conditions
- Author
-
Yinghua Yu, Yun Liao, Chunsen Li, Xueliang Huang, Gui Chen, and Qianqian Lu
- Subjects
chemistry.chemical_classification ,010405 organic chemistry ,chemistry.chemical_element ,Regioselectivity ,Alkyne ,General Chemistry ,010402 general chemistry ,01 natural sciences ,Combinatorial chemistry ,Catalysis ,Cycloaddition ,0104 chemical sciences ,Rhodium ,chemistry.chemical_compound ,chemistry ,Click chemistry ,Structural isomer ,Organic chemistry ,Azide - Abstract
A rhodium-catalyzed azide–alkyne cycloaddition of internal ynamides is described. The reaction could be performed in a wide range of solvents, including aqueous media, under mild conditions without careful exclusion of air and moisture, giving a variety of 5-amino-triazoles as a single regioisomer. The mechanism of regioselective cycloaddition was rationalized by means of density functional theory calculations.
- Published
- 2017
14. Beryllium and boron decoration form planar tetracoordinate carbon strips at the edge of BCN nanoribbons result in energy gap opposite variation and third-order nonlinear optical response improvement
- Author
-
Minyi Zhang, Jing Wei, Peng Wu, Jinshuai Song, Qianqian Lu, and Chunsen Li
- Subjects
Materials science ,Tetracoordinate ,Band gap ,Graphene ,General Physics and Astronomy ,chemistry.chemical_element ,02 engineering and technology ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,Molecular physics ,Two-photon absorption ,0104 chemical sciences ,law.invention ,chemistry.chemical_compound ,chemistry ,Computational chemistry ,Boron nitride ,law ,Density functional theory ,Physical and Theoretical Chemistry ,0210 nano-technology ,Boron ,Graphene nanoribbons - Abstract
Planar tetracoordinate carbon (ptC) with intriguing planar bond structure has triggered great attentions. In this work, B/Be-terminated decoration form armchair hybridized boron nitride and graphene nanoribbons with ptC structure (ptC-aBCNNRs) are investigated theoretically for third-order nonlinear optical (NLO) response by employing time-dependent density functional theory combined with sum-over-states method. Our calculations reveal Be and B decorated on ptC-aBCNNRs would result in opposite variation of energy gaps, and strongly enhance the NLO response in different third-order NLO processes. The strong third-order NLO response predicted for ptC-aBCNNRs is originated from the charge redistribution induced by ptC structure and hexagonal-BN ribbon insertion.
- Published
- 2017
15. Highly Efficient CO2 Electrolysis on Cathodes with Exsolved Alkaline Earth Oxide Nanostructures
- Author
-
Changchang Pan, Lizhen Gan, Lingting Ye, Chunsen Li, Minyi Zhang, Kui Xie, and Fanglin Chen
- Subjects
Electrolysis ,Alkaline earth metal ,Materials science ,Nanostructure ,Inorganic chemistry ,Oxide ,02 engineering and technology ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,Cathode ,Titanate ,0104 chemical sciences ,law.invention ,chemistry.chemical_compound ,Adsorption ,chemistry ,law ,General Materials Science ,0210 nano-technology ,Perovskite (structure) - Abstract
The solid oxide CO2 electrolyzer has the potential to provide storage solutions for intermittent renewable energy sources as well as to reduce greenhouse gas emissions. One of the key challenges remains the poor adsorption and activity toward CO2 reduction on the electrolyzer cathode at typical operating conditions. Here, we show a novel approach in tailoring a perovskite titanate (La, Sr)TiO3+δ cathode surface, by the in situ growing of SrO nanoislands from the host material through the control of perovskite nonstoichiometry. These nanoislands provide very enhanced CO2 adsorption and activation, with stability up to 800 °C, which is shown to be in an intermediate form between carbonate ions and molecular CO2. The activation of adsorbed CO2 molecules results from the interaction of exsolved SrO nanoislands and the defected titanate surface as revealed by DFT calculations. These cathode surface modifications result in an exceptionally high direct CO2 electrolysis performance with current efficiencies near 100%.
- Published
- 2017
16. Highly Chemoselective and Enantioselective Catalytic Oxidation of Heteroaromatic Sulfides via High-Valent Manganese(IV)–Oxo Cation Radical Oxidizing Intermediates
- Author
-
Shuang Gao, Wen Dai, Ying Lv, Guosong Li, Chunsen Li, and Sensen Shang
- Subjects
010405 organic chemistry ,Sulfoxide ,General Chemistry ,Benzoxazole ,010402 general chemistry ,01 natural sciences ,Medicinal chemistry ,Heterolysis ,Catalysis ,0104 chemical sciences ,chemistry.chemical_compound ,chemistry ,Benzothiazole ,Pyridine ,Organic chemistry ,Hydrogen peroxide ,Thiazole - Abstract
A manganese complex with a porphyrin-like ligand that catalyzes the highly chemoselective and enantioselective oxidation of heteroaromatic sulfides, including imidazole, benzimidazole, indole, pyridine, pyrimidine, pyrazine, sym-triazine, thiophene, thiazole, benzothiazole, and benzoxazole, with hydrogen peroxide is described, furnishing the corresponding sulfoxides in good to excellent yields and enantioselectivities (up to 90% yield and up to >99% ee) within a short reaction time (0.5 h). The practical utility of the method has been demonstrated in the gram-scale synthesis of chiral sulfoxide. Mechanistic studies, performed with 18O-labeled water (H218O), hydrogen peroxide (H218O2), and cumyl hydroperoxide, reveal that a high-valent manganese–oxo species is generated as the oxygen atom delivering agent via carboxylic acid assisted heterolysis of O–O bonds. Density functional theory (DFT) calculations were also carried out to give further insight into the mechanism of manganese-catalyzed sulfoxidation. O...
- Published
- 2017
17. Enhancing CO2 electrolysis through synergistic control of non-stoichiometry and doping to tune cathode surface structures
- Author
-
Ping Huang, Lingting Ye, Minyi Zhang, Kui Xie, Guo-Cong Guo, Maochun Hong, Chunsen Li, John T. S. Irvine, EPSRC, The Royal Society, University of St Andrews. School of Chemistry, and University of St Andrews. EaSTCHEM
- Subjects
Materials science ,Science ,Oxide ,General Physics and Astronomy ,02 engineering and technology ,010402 general chemistry ,01 natural sciences ,7. Clean energy ,Redox ,E-NDAS ,General Biochemistry, Genetics and Molecular Biology ,Article ,law.invention ,chemistry.chemical_compound ,Adsorption ,law ,QD ,SDG 7 - Affordable and Clean Energy ,Electrolysis ,Multidisciplinary ,Dopant ,Doping ,General Chemistry ,021001 nanoscience & nanotechnology ,QD Chemistry ,Cathode ,0104 chemical sciences ,Chemical state ,chemistry ,Chemical engineering ,0210 nano-technology - Abstract
Sustainable future energy scenarios require significant efficiency improvements in both electricity generation and storage. High-temperature solid oxide cells, and in particular carbon dioxide electrolysers, afford chemical storage of available electricity that can both stabilize and extend the utilization of renewables. Here we present a double doping strategy to facilitate CO2 reduction at perovskite titanate cathode surfaces, promoting adsorption/activation by making use of redox active dopants such as Mn linked to oxygen vacancies and dopants such as Ni that afford metal nanoparticle exsolution. Combined experimental characterization and first-principle calculations reveal that the adsorbed and activated CO2 adopts an intermediate chemical state between a carbon dioxide molecule and a carbonate ion. The dual doping strategy provides optimal performance with no degradation being observed after 100 h of high-temperature operation and 10 redox cycles, suggesting a reliable cathode material for CO2 electrolysis., Carbon dioxide electrolysers are promising for chemical storage of renewable electricity; however, achieving effective adsorption/activation of CO2 is still an issue. Here the authors make a perovskite titanate cathode where non-stoichiometry and chemical doping are used to tune the surface structures, facilitating CO2 reduction.
- Published
- 2017
18. Bonding and Diels–Alder reactions of substituted 2-borabicyclo(1.1.0)but-1(3)-enes: a theoretical study
- Author
-
Congjie Zhang, Chunsen Li, Jinshuai Song, Zhimin Wang, and Yirong Mo
- Subjects
010304 chemical physics ,Ionic bonding ,Cyclopropene ,010402 general chemistry ,01 natural sciences ,Cycloaddition ,0104 chemical sciences ,chemistry.chemical_compound ,Propellane ,chemistry ,Computational chemistry ,0103 physical sciences ,Valence bond theory ,Physical and Theoretical Chemistry ,Carbene ,Antiaromaticity ,Diels–Alder reaction - Abstract
Substituted 2-borabicyclo(1.1.0)but-1(3)-enes (2BB’s) are a kind of novel molecules with inverted carbon–carbon bonds whose orders range between one and two. Considering the significant interest in the Diels–Alder (D–A) reactions of substituted cyclopropenes, here we studied the bonding and D–A reactions of 24 substituted 2BB molecules at the B3LYP-D3/6-311G** theoretical level. Computations showed that the inverted C=C bond lengths fall in the range of 1.46–1.50 A and 2BB is of significant characteristic of a singlet biradical with two σ single electrons and π aromatic conjugation over the three-membered rings. Yet ab initio valence bond computations showed that the inverted bonds are charge-shifted, and the ionic resonance structures arising from charge-shifting are of carbene characteristics as well. Thus, substituted 2BB’s can also be considered as B-heterocyclic carbenes. Since the LUMOs of the 2BB derivatives are similar to those of ethene and cyclopropene, we studied their D–A reactions with butadiene. All cycloaddition reactions kinetically and thermodynamically favor the formation of the derivatives of 7-bora-oct-3-ene[4.1.1]propellane undergoing endo transition states. Notably, there is a good correlation between the reaction barriers and the hyperconjugative aromatic and antiaromatic stabilization enthalpies for all substituted 2BB’s. In other words, the differences in their reactivity result from the difference in their aromatic stability.
- Published
- 2019
19. Why Do Colloidal Wurtzite Semiconductor Nanoplatelets Have an Atomically Uniform Thickness of Eight Monolayers?
- Author
-
Guohua Jia, Fei Wang, Lihong Liu, Chunsen Li, Amit Sitt, Shaomin Liu, Shaghraf Javaid Anwar, Dechao Chen, Minyi Zhang, Martin Saunders, Matthew R. Rowles, Yingping Pang, and Wei Chen
- Subjects
Materials science ,business.industry ,Growth kinetics ,02 engineering and technology ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,Surface energy ,0104 chemical sciences ,Colloid ,Semiconductor ,Chemical engineering ,Monolayer ,General Materials Science ,Density functional theory ,Physical and Theoretical Chemistry ,0210 nano-technology ,business ,Wurtzite crystal structure - Abstract
Herein we employed a first-principles method based on density functional theory to investigate the surface energy and growth kinetics of wurtzite nanoplatelets to elucidate why nanoplatelets exhibit a uniform thickness of eight monolayers. We synthesized a series of wurtzite nanoplatelets (ZnSe, ZnS, ZnTe, and CdSe) with an atomically uniform thickness of eight monolayers. As a representative example, the growth mechanism of 1.39 nm thick (eight monolayers) wurtzite ZnSe nanoplatelets was studied to substantiate the proposed growth kinetics. The results show that the growth of the seventh and eighth layers along the [112̅0] direction of 0.99 nm (six monolayers) ZnSe magic-size nanoclusters is accessible, whereas the growth of the ninth layer is unlikely to occur because the formation energy is large. This work not only gives insights into the synthesis of atomically uniform thick wurtzite semiconductor nanoplatelets but also opens up new avenues to their applications in light-emitting diodes, catalysis, detectors, and lasers.
- Published
- 2019
20. Easy access to medium-sized lactones through metal carbene migratory insertion enabled 1,4-palladium shift
- Author
-
Chunsen Li, Xueliang Huang, Lei Zhu, Pushkin Chakraborty, Jinshuai Song, and Yinghua Yu
- Subjects
inorganic chemicals ,Science ,General Physics and Astronomy ,chemistry.chemical_element ,Synthetic chemistry methodology ,010402 general chemistry ,Ring (chemistry) ,01 natural sciences ,General Biochemistry, Genetics and Molecular Biology ,Article ,Metal ,Benzaldehyde ,chemistry.chemical_compound ,Molecule ,lcsh:Science ,Multidisciplinary ,010405 organic chemistry ,Chemistry ,Catalytic mechanisms ,Migratory insertion ,General Chemistry ,Homogeneous catalysis ,Combinatorial chemistry ,0104 chemical sciences ,Lactone synthesis ,visual_art ,visual_art.visual_art_medium ,lcsh:Q ,Carbene ,Palladium - Abstract
Reactions that efficiently construct medium-sized lactones are significant, as they overcome the unfavorable entropic factor and transannular interactions for ring closure, and the lactones produced are common structural motifs recurring in many biologically active compounds. Herein, we describe a valuable strategy for medium-sized lactone synthesis by accomplishing site-selective C–H bond functionalization via a palladium carbene migratory insertion enabled 1,4-palladium shift. The overall process achieves the formal dimerization of two readily available benzaldehyde derivatives, providing value-added products medium-sized lactones. Our method is amenable to late-stage modification of approved drugs and other complex molecules. Mechanistic studies including deuterium-labeling experiments and DFT calculation shed light on the reaction pathways., Transannular construction of medium-sized lactones is entropically unfavoured. Herein, the authors describe a strategy for valuable medium-sized lactone synthesis from available benzaldehydes by selective C-H bond functionalization via palladium carbene migratory insertion-enabled 1,4-palladium shift.
- Published
- 2019
21. Selective Chlorination of Substrates by the Halogenase SyrB2 Is Controlled by the Protein According to a Combined Quantum Mechanics/Molecular Mechanics and Molecular Dynamics Study
- Author
-
Dina A. Sharon, Chunsen Li, Sason Shaik, Jing Huang, Binju Wang, and Wei Wu
- Subjects
chemistry.chemical_classification ,Reaction mechanism ,010405 organic chemistry ,Ligand ,Chemistry ,Hydrogen bond ,Halogenation ,General Chemistry ,010402 general chemistry ,Hydrogen atom abstraction ,01 natural sciences ,Catalysis ,0104 chemical sciences ,Molecular dynamics ,Computational chemistry ,Isomerization ,Alkyl - Abstract
The enzyme SyrB2 employs an FeIV–oxo species to achieve selective C–H halogenation of l-threonine. Herein, we use combined quantum mechanical/molecular mechanical (QM/MM) calculations and molecular dynamics (MD) simulations to decipher the mechanism of selective halogenation by SyrB2. Our QM/MM calculations show the presence of three Cl–FeIV–oxo isomers which interconvert, and only the one having its oxo ligand pointing toward the target C–H bond is active during the hydrogen atom abstraction (H-abstraction) process. The fate of the formed Cl–FeIII–OH/R• intermediate is determined by a hydrogen-bonding interaction between the Arg254 residue and the OH ligand of Cl–FeIII–OH. The hydrogen bond not only prevents the OH group from participating in the followup rebound step to form a hydroxylated product but also facilitates the isomerization of the Cl–FeIII–OH/R• intermediate so that the Cl is directed toward the alkyl radical. The role of Arg254 in regulating the selectivity of chlorination is further discus...
- Published
- 2016
22. Silver‐Laden Black Phosphorus Nanosheets for an Efficient In Vivo Antimicrobial Application
- Author
-
Chunsen Li, Fuan Wang, Minyi Zhang, Kang Ma, Shanshan Yu, Yingying Chen, Xiaoqing Liu, Meijuan Liang, and Qiong Wu
- Subjects
Silver ,Nanotechnology ,02 engineering and technology ,010402 general chemistry ,01 natural sciences ,Black phosphorus ,Silver nanoparticle ,Nanomaterials ,Biomaterials ,In vivo ,Animals ,General Materials Science ,Pathogen inactivation ,Skin ,Nanosheet ,Wound Healing ,Bacteria ,Chemistry ,Phosphorus ,Bacterial Infections ,General Chemistry ,021001 nanoscience & nanotechnology ,Antimicrobial ,Anti-Bacterial Agents ,Nanostructures ,Rats ,0104 chemical sciences ,Reactive oxygen species generation ,0210 nano-technology ,Biotechnology - Abstract
Nanobactericides represent one of the most efficient and promising strategies for eliminating bacterial infection considering the increasing resistance threats of conventional antibiotics. Black phosphorus (BP) is the most exciting postgraphene layered 2D nanomaterial with convincing physiochemical properties, yet the study of BP-based antibiotics is still in its infancy. Here, a compact silver nanoparticle (AgNP)-doped black phosphorus nanosheet (BPN) is constructed to synergistically enhance solar disinfection through the promoted reactive oxygen species (ROS) photogeneration, which is attributed to the improved electron-hole separation and recombination of BPNs as revealed from the systematic experimental studies. An in-depth density functional theory (DFT) calculation confirms that the integrated AgNPs provide a preferred site for facilitating the adsorption and activation of O2 , thus promoting the more efficient and robust ROS generation on BPN-AgNP nanohybrids. Besides the enhanced photoinduced ROS, the anchored AgNPs simultaneously lead to a dramatically increased affinity toward bacteria, which facilitates a synergetic pathogen inactivation. Significantly, the convincing antimicrobial BPN-AgNP contributes to the prominent wound healing and antimicrobial ability in vivo with minimized biological burden. This sophisticated design of new 2D nanohybrids opens a new avenue for further exploiting BP-based nanohybrids in portable bandage and broad-spectrum disinfection applications.
- Published
- 2020
23. Highly efficient electrochemical reforming of CH 4 /CO 2 in a solid oxide electrolyser
- Author
-
Changli Zhu, Fanglin Chen, Wenlie Lin, Chunsen Li, Changchang Pan, Jinhai Lu, John P. Lemmon, and Kui Xie
- Subjects
Materials science ,Materials Science ,Oxide ,02 engineering and technology ,010402 general chemistry ,Electrochemistry ,7. Clean energy ,01 natural sciences ,Redox ,Catalysis ,law.invention ,chemistry.chemical_compound ,law ,Research Articles ,Electrolysis ,Multidisciplinary ,SciAdv r-articles ,021001 nanoscience & nanotechnology ,Cathode ,0104 chemical sciences ,Anode ,Chemical engineering ,chemistry ,0210 nano-technology ,Research Article ,Syngas - Abstract
Electrochemical reforming of CH4/CO2 is demonstrated in a solid oxide electrolyser., Reforming CH4 into syngas using CO2 remains a fundamental challenge due to carbon deposition and nanocatalyst instability. We, for the first time, demonstrate highly efficient electrochemical reforming of CH4/CO2 to produce syngas in a solid oxide electrolyser with CO2 electrolysis in the cathode and CH4 oxidation in the anode. In situ exsolution of an anchored metal/oxide interface on perovskite electrode delivers remarkably enhanced coking resistance and catalyst stability. In situ Fourier transform infrared characterizations combined with first principle calculations disclose the interface activation of CO2 at a transition state between a CO2 molecule and a carbonate ion. Carbon removal at the interfaces is highly favorable with electrochemically provided oxygen species, even in the presence of H2 or H2O. This novel strategy provides optimal performance with no obvious degradation after 300 hours of high-temperature operation and 10 redox cycles, suggesting a reliable process for conversion of CH4 into syngas using CO2.
- Published
- 2018
24. Aminofluorination: transition-metal-free N-F bond insertion into diazocarbonyl compounds
- Author
-
Chunsen Li, Xueliang Huang, Xuesong Luo, Yinghua Yu, Jinshuai Song, and Gui Chen
- Subjects
010405 organic chemistry ,chemistry.chemical_element ,General Chemistry ,010402 general chemistry ,Photochemistry ,01 natural sciences ,0104 chemical sciences ,Catalysis ,Chemistry ,chemistry ,Transition metal ,Computational chemistry ,Fluorine ,Nitrogen source ,Potential mechanism - Abstract
Gem-aminofluorination of diazocarbonyl compounds has been achieved for the first time., Gem-aminofluorination of diazocarbonyl compounds has been achieved for the first time. This reaction proceeds under mild conditions and does not require any transition-metal promoter or catalyst. Treatment of diazoesters with N-fluorobenzenesulfonimide (NFSI), which serves as both a fluorine and nitrogen source, results in the facile construction of C–N and C–F bonds, providing aminofluorination products in moderate to excellent yields. Kinetic studies and DFT calculations have provided valuable insight into the potential mechanism for this novel N–F bond insertion.
- Published
- 2015
Catalog
Discovery Service for Jio Institute Digital Library
For full access to our library's resources, please sign in.